Communication switches, as commonly used in telephone equipment are well known. An example is shown in U.S. Pat. No. 4,688,212 Centralized Image Response of Telephone Time Slot Interchange System. Such systems are typically divided into two parts. The first part is the central processing unit or the CPU. The CPU provides the functions of digit analysis, routing algorithms, special features such as speed dialing and billing or call authorization. A second part of the telephone switch generally identified as a Switching Unit provides the functions of call processing including port or slot switching and the transmission of PCM or voice data or signaling data to the designated ports or slots. Certain direct functions, as are well known, are performed by the Switching Unit. These are provision of an off hook signal, digit manipulation, and call acknowledgment.
The CPU provides disk storage, a master processing unit (MPU), a bus master arbiter to control transmissions from the main processing unit to the Switching Unit (C Bus service unit) and a serial bus interface unit (SBIU) controlling the information within the modules of the MPU.
In the Switching Unit, a Telephone Switching Unit (TSU) and signal Switching Unit (SSU) provides access between the slots or ports in the telephone switch for external connection of the telephone switch to a central office or to other ports or slots in the telephone switch. For example, the TSU may provide a direct connection for PC voice and signaling information to a peripheral card which may connect externally to a digital trunk unit such as T1 unit as used in the U.S. or an E1 unit as used internationally, for connection to central offices, or direct connection to another port or slot. The SSU may provide a direct connection to another port in that SSU or to another port connected to another SSU within the switch or for the external connection to that port or slot in another SSU or TSU.
In the process of using a telephone switch, information may be received from an external source, such as a T1 trunk. This information may be in the form of a designated communication protocol required to be interpreted in terms of that designated protocol by the telephone switch. That interpreted protocol may then be used to construct or remove connections for telephone communications transaction. Accordingly, information received from an external source may be required to be interpreted as protocols by software programs in the telephone switch. Provision for adding or deleting these software programs relating to these protocols and for interpreting the information processed from these protocols should be made available and easy to add, delete or change. After processing of the protocol information, there is a requirement for transmitting the processed information from the Switching Unit to the central processing unit. This communication using the buses internal to the telephone switch for communicating the processed or interpreted protocol information between the Switching Unit and the central processing unit reduces the speed of the telephone switch.
As seen, information may be received relating to particular communications protocols. This protocol information is processed and then the processed information is used by the telephone switch, for example, to establish and reduce circuit switch telephone calls and complete transactions. As protocols change and a telephone switch is required to process a plurality of protocols, a capability for modularly adding protocols and the equipment for processing the information within the protocols facilitates use of the switch. Additionally, a telephone processor should have capability for transmission of the processed protocol information to its central processor where that information is designated for use in establishing telephone routing within the switch.